The most accurate information available to a pilot about an aircraft's position, motion, and attitude are exterior visual cues (e.g., the Earth's horizon) and the aircraft's flight instruments. When exterior visual cues are unavailable, such as when the horizon is not visible, a pilot should rely on the aircraft's flight instruments. However, when the pilot's attention is distracted from the attitude or altitude instruments or the pilot has limited instrument flight time, the pilot may instead rely on sensory information provided by the pilot's vestibular system (e.g., organs of equilibrium located in the inner ear) and/or proprioceptive system (e.g., receptors located in the skin, muscles, tendons, and joints).
Under certain circumstances, an aircraft pilot may experience spatial disorientation, which refers to a condition when a pilot's sense of the aircraft's attitude or rotation is incorrect and is based on misinterpreted sensory information. For example, when a pilot initiates a banking right turn, the pilot's inner ear may detect the roll into the turn. However, if the turn is held constant, the pilot's inner ear quickly may compensate, and the pilot inaccurately may sense that the aircraft has returned to level flight. Accordingly, when the pilot subsequently levels the wings, the pilot may perceive that the aircraft is banking to the left. In the absence of exterior visual references to counteract the sensation, the pilot may rely on the sensory illusion produced by the inner ear, and spatial disorientation may result.
It is extremely dangerous for a pilot to fly under a sustained condition of spatial disorientation, particularly if the pilot is not adequately trained to rely on the aircraft instruments, because the condition may cause the pilot to enter an unsafe maneuver and/or to lose control of the aircraft. Several dangerous illusions that may occur as a pilot is experiencing spatial disorientation include the “graveyard spin,” the “graveyard spiral,” and the “Coriolis illusion.” Any one of these illusions, if not recognized and compensated for in adequate time, may result in an excessive loss of altitude and an impact with terrain.
Although non instrument-rated pilots are prohibited from flying under limited visibility conditions in which spatial disorientation is likely, significant numbers of general aviation accidents that are attributable to spatial orientation continue to occur. Accordingly, it is desirable to provide methods and apparatus for assisting pilots under conditions in which spatial disorientation is likely to be present. Other desirable features and characteristics of the embodiments will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.